Hello jay d and welcome to Chevy Chatter!
You'll find answers to most any question you have about your '31 on this site.
I'll try to help with some of your questions. Going in reverse order of your posting, here are some people/firms which make wood replacements for your pick up. I've not had any personal experiences with any of them, but others in the VCCA, and on this site, have.
Jim Rodman:
http://www.autowood.net/KC Wood Mfg:
http://www.chevywood.com/Classic Wood Mfg
Mr. Goodwood
1006 N. Raleigh St.
Greensboro, North Carolina 27405
336-691-1344
As for the brakes, it may be a simple matter of not having the proper linings. These old mechanical systems required a "soft" woven lining. The hard linings used with hydraulic systems simply won't cut it on the mechanical systems. You can get these linings at industrial friction/brake shops, or, you can have them relined properly by contacting The Filling Station.
www.fillingstation.comBesides having the proper linings, the brake linkages need to be adjusted correctly. The Repair Manual (also available from The Filling Station) explains how this is done. By the way, when adjusted properly, with the correct linings, the braking system works just fine. So don't let anyone tell you it is necessary to "upgrade" to an hydraulic one.
And, as an added bonus to owning a '31, check out this site:
http://1931chevrolet.com/It is run by our own Chevy Chatter webmaster, Bill Barker, and has loads of good info.
Once again, welcome, and Happy Motoring,
Dan